1. I CHEMISTRY

2. A. Composition of Matter
Matter - Everything in universe is composed of matter
Matter is anything that occupies space or has mass
Mass – quantity of matter an object has
Weight – pull of gravity on an object

3. B. Elements
Pure substances that cannot be broken down chemically into simpler kinds of matter
More than 100 elements (92 naturally occurring)

4. 90% of the mass of an organism is composed of 4 elements (oxygen, carbon, hydrogen and nitrogen)
Each element unique chemical symbol
Consists of 1-2 letters
First letter is always capitalized

5. C. Atoms
The simplest particle of an element that retains all the properties of that element
Properties of atoms determine the structure and properties of the matter they compose
Our understanding of the structure of atoms based on scientific models, not observation

6. The Nucleus Central core
Consists of positive charged protons and neutral neutrons
Positively charged
Contains most of the mass of the atom

7. The Protons
All atoms of a given element have the same number of protons
Number of protons called the atomic number
Number of protons balanced by an equal number of negatively charged electrons

8. The Neutrons
The number varies slightly among atoms of the same element
Different number of neutrons produces isotopes of the same element

9. Atomic Mass Protons & neutrons are found in the nucleus of an atom
Protons and neutrons each have a mass of 1 amu (atomic mass unit)
The atomic mass of an atom is found by adding the number of protons & neutrons in an atom

10. The Electrons
Negatively charged high energy particles with little or no mass
Travel at very high speeds at various distances (energy levels) from the nucleus

11. Electrons in the same energy level are approximately the same distance from the nucleus
Outer energy levels have more energy than inner levels
Each level holds only a certain number of electrons

12. Energy Levels Atoms have 7 energy levels
The levels are K (closest to the nucleus), L, M, N, O, P, Q (furthest from the nucleus)
The K level can only hold 2 electrons
Levels L – Q can hold 8 electrons (octet rule)

14. Compounds Most elements do not exist by themselves
Readily combine with other elements in a predictable fashion

15. A compound is a pure substance made up of atoms of two or more elements
The proportion of atoms are always fixed
Chemical formula shows the kind and proportion of atoms of each element that occurs in a particular compound

16. Molecules are the simplest part of a substance that retains all of the properties of the substance and exists in a free state
Some molecules are large and complex

17. Chemical Formulas
Subscript after a symbol tell the number of atoms of each element
H20 has 2 atoms of hydrogen & 1 atom of oxygen
Coefficients before a formula tell the number of molecules
3O2 represents 3 molecules of oxygen or (3x2) or 6 atoms of oxygen

18. The physical and chemical properties of a compound differ from the physical and chemical properties of the individual elements that compose it

19. The tendency of elements to combine and form compounds depends on the number and arrangement of electrons in their outermost energy level
Atoms are most stable when their outer most energy level is filled

20. Most atoms are not stable in their natural state
Tend to react (combine) with other atoms in order to become more stable (undergo chemical reactions)
In chemical reactions bonds are broken; atoms rearranged and new chemical bonds are formed that store energy

21. Covalent Bonds
Formed when two atoms share one or more pairs of electrons

22. Ionic Bonds Some atoms become stable by losing or gaining electrons
Atoms that lose electrons are called positive ions

23. Atoms that gain electrons are called negative ions
Because positive and negative electrical charges attract each other ionic bonds form

24. Energy and Matter Energy The ability to do work or cause change
Occurs in various forms
Can be converted to another form
Forms important to biological systems are chemical, thermal, electrical and mechanical energy
Free energy is the energy in a system that is available for work

25. States of Matter Atoms are in constant motion
The rate at which atoms or molecules in a substance move determines its state

26. Solid Molecules tightly linked together in a definite shape
Vibrate in place
Fixed volume and shape

27. Liquids Molecules not as tightly linked as a solid
Maintain fixed volume
Able to flow and conform to shape of container

28. Gas
Molecules have little or no attraction to each other
Fill the volume of the occupied container
Move most rapidly
To cause a substance to change state, thermal energy (heat) must be added to or removed from a substance

29. Certain chemical substances (catalysts) reduce the amount of activation energy required
Biological catalysts are called enzymes

30. Enzymes are an important class of catalysts in living organisms
Mostly protein
Thousands of different kinds
Each specific for a different chemical reaction

31. Enzyme Structure Enzymes work on substances called substrates
Substrates must fit into a place on an enzyme called the active site
Enzymes are reusable!

32. Solutions

33. Solutions
A solution is a mixture in which 2 or more substances are uniformly distributed in another substance

34. Water is the universal solvent
Solute is the substance dissolved in the solution
Particles may be ions, atoms, or molecules
Solvent is the substance in which the solute is dissolved
Water is the universal solvent

35. Solutions can be composed of varying proportions of a given solute in a given solvent --- vary in concentration (measurement of the amount of solute)
A saturated solution is one in which no more solute can be dissolved
Aqueous solution (water) are universally important to living things

36. Dissociation of water
Breaking apart of the water molecule into two ions of opposite charge (due to strong attraction of oxygen atom of one molecule for H atom of another water molecule)
H2O  H+ (hydrogen ion) + OH- (hydroxide ion)
H+ + H2O  H3O (hydronium ion)

37. Acids and Bases
One of the most important aspects of a living system is the degree of acidity or alkalinity

38. Acids
Number of hydronium ions in solutions is greater than the number of hydroxide ions
HCl  H+ + Cl-

39. Bases
Number of hydroxide ions in solution is greater than the number of hydronium ions
NaOH  Na+ + OH-

40. pH Scale
logarithmic scale for comparing the relative concentrations of hydronium ions and hydroxide ions in a solution
ranges from 0 to 14
Each pH is 10X stronger than next
e.g. ph 1 is 10 times stronger than ph 2

41. the lower the pH the stronger the acid
the higher the pH the stronger the base
pH 7.0 is neutral

42. Buffers Control of pH is very important
Most enzymes function only within a very narrow pH
Control is accomplished with buffers made by the body
Buffers keep a neutral pH (pH 7)

43. Buffers neutralize small amounts of either an acid or base added to a solution
Complex buffering systems maintain the pH values of your body’s many fluids at normal and safe levels